The invention relates to an air-cleaner including an adsorption element to adsorb a vaporized fuel returned from the engine side to the induction system.
An internal combustion engine has an induction system to produce the following phenomenon. A vaporized fuel leaked from an injector, a vapor flowing back from the purge circuit of a canister, a refluxed blow-by gas and the like during stopping the engine are returned from the engine side to the induction system. Therefore, the technical field of internal combustion engines has conventionally taken various measures to prevent the returned vaporized fuel from being discharged into the atmosphere to pollute the air.
In recent years, there has been proposed an induction system including adsorption means containing an adsorbent and adsorbing a vaporized fuel in the induction system. The invention disclosed in Japanese Patent Application Laid-open No. 2002-155815 is one example of the above technique.
An air-cleaner disclosed in Japanese Patent Application Laid-Open No. 2002-155815 adsorbs the vaporized fuel inside the air-cleaner. The air-cleaner includes a housing and a filter element. The filter element is arranged to separate the interior of the air-cleaner into a dust side and a clean side. The dust side has an introduction portion for introducing the air. The clean side has a feeder portion for feeding filtered air to an engine. The air-cleaner also includes, on the clean side of the filter element, a plate-shaped adsorption element containing an adsorbent. The adsorption element is arranged parallel to the filter element on the clean side in the housing. The adsorption element is arranged to cover up the entire cross-section of the housing. Furthermore, the air-cleaner includes a variable vane on the clean side to adjust a circulation region of the air circulating in the housing.
According to the invention disclosed in Japanese Patent Application Laid-Open No. 2002-155815, the adsorption element certainly covers up the entire cross-section of the housing in the housing of the air-cleaner. The disclosed structure prevents the vaporized fuel returned from the engine side from flowing out into the air side relative to the air-cleaner.
This structure, however, causes air to necessarily pass through the adsorption element during air inspiration, and the adsorption element increases a passage resistance of the air.